SE1451471A1 - A method for controlling a waste heat recovery system and a waste heat recovery system - Google Patents
A method for controlling a waste heat recovery system and a waste heat recovery system Download PDFInfo
- Publication number
- SE1451471A1 SE1451471A1 SE1451471A SE1451471A SE1451471A1 SE 1451471 A1 SE1451471 A1 SE 1451471A1 SE 1451471 A SE1451471 A SE 1451471A SE 1451471 A SE1451471 A SE 1451471A SE 1451471 A1 SE1451471 A1 SE 1451471A1
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- Prior art keywords
- heat exchanger
- coolant fluid
- mass flow
- exhaust gas
- determining
- Prior art date
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- 238000000034 method Methods 0.000 title claims abstract description 53
- 239000002918 waste heat Substances 0.000 title claims abstract description 39
- 238000011084 recovery Methods 0.000 title claims abstract description 32
- 239000002826 coolant Substances 0.000 claims abstract description 131
- 239000012530 fluid Substances 0.000 claims abstract description 109
- 239000007789 gas Substances 0.000 claims abstract description 70
- 238000002485 combustion reaction Methods 0.000 claims abstract description 24
- 102100022057 Hepatocyte nuclear factor 1-alpha Human genes 0.000 claims abstract description 6
- 101001045751 Homo sapiens Hepatocyte nuclear factor 1-alpha Proteins 0.000 claims abstract description 6
- 238000004590 computer program Methods 0.000 claims description 19
- 238000011144 upstream manufacturing Methods 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 6
- 230000004044 response Effects 0.000 claims description 4
- 238000013500 data storage Methods 0.000 claims 2
- 238000004422 calculation algorithm Methods 0.000 description 9
- 238000013021 overheating Methods 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
- F02G5/00—Profiting from waste heat of combustion engines, not otherwise provided for
- F02G5/02—Profiting from waste heat of exhaust gases
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N5/00—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy
- F01N5/02—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy the devices using heat
- F01N5/025—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy the devices using heat the device being thermoelectric generators
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
- F01N2240/02—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being a heat exchanger
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
- F01N2240/20—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being a flow director or deflector
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2410/00—By-passing, at least partially, exhaust from inlet to outlet of apparatus, to atmosphere or to other device
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
- F01N2900/06—Parameters used for exhaust control or diagnosing
- F01N2900/14—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust gas
- F01N2900/1404—Exhaust gas temperature
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
- F01N2900/06—Parameters used for exhaust control or diagnosing
- F01N2900/14—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust gas
- F01N2900/1411—Exhaust gas flow rate, e.g. mass flow rate or volumetric flow rate
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N9/00—Electrical control of exhaust gas treating apparatus
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Exhaust Gas After Treatment (AREA)
- Air-Conditioning For Vehicles (AREA)
- Engine Equipment That Uses Special Cycles (AREA)
Description
15 20 25 30 mass flow of exhaust gas through each of the exhaust channel and the bypass channel can be adjusted, and a coolant channel through the TEG. The adjustable valve can be adjusted in response to the measured or configured to carry a coolant fluid estimated temperature of the exhaust gases. lf the exhaust gases are too hot or too cold, a portion of the exhaust gases are led through the bypass channel in order to protect the TEG.
Thus, the system is primarily configured to protect the TEG from overheating.
SUMMARY OF THE INVENTION lt is an object of the present invention to provide on one hand a method for controlling a waste heat recovery system for recovering waste heat from a combustion engine in a drive system, and on the other hand a waste heat recovery system, which are in at least some aspect improved with respect to previously known methods and systems.
According to the invention, this object is with respect to the method achieved by means of a method according to the appended claim 1. With the inventive method, the waste heat recovery system can be controlled so that the net power gain Pnet of the drive system is maximized, rather than the power gain of the at least one heat exchanger. The net power gain Pnel is here defined as the sum of the total power gains obtainable from the waste heat recovery system and the total power losses arising in the drive system as a result of the waste heat recovery system. ln consequence, in a vehicle with a drive system comprising said 10 15 20 25 waste heat recovery system, the fuel economy may be improved by using the method according to the present invention.
Preferably, but not necessarily, the heat exchanger is placed in an after treatment system of the drive system.
According to an embodiment of the invention, the step of determining the setpoint S1 for the mass flow lVlFEc1 of exhaust gas through the first heat exchanger comprises the steps of: - choosing a set of test values representing the mass flow IVIFEG1 of exhaust gas through the first heat exchanger, - iteratively calculating the net power gain Pm using said test values until said net power gain Pm is at a maximum, - outputting the test value at which the net power gain Pnef is at a maximum as said setpoint S1. ln this embodiment, the setpoint S1 is determined using an iterative algorithm for calculating the net power gain Pne1. The set of test values is preferably chosen such that the initial net power gain Pm is small. After each iteration, it is checked whether the net power gain Pne1 is larger than in the previous iteration, and if so, the algorithm continues to calculate the net power gain for the successive test value. lf not, the preceding test value is output as the setpoint S1. ln this way, the setpoint S1 can be found within a short running time.
According to another embodiment of the invention, wherein the system further comprises a cooler connected to the first coolant channel and a coolant fluid pump, the method further comprises the steps of: 10 15 20 25 - determining a setpoint S2 for the mass flow MFcF of coolant fluid pumped through the coolant fluid pump at which the net power gain Pnet of the drive system is at a maximum, - controlling the coolant fluid pump so that the mass flow MFcF of coolant fluid pumped through the coolant fluid pump is adjusted toward the determined setpoint S2. ln this embodiment, the method is implemented in a system comprising a cooling system with a coolant fluid pump. ln addition to controlling the first adjustable valve controlling the amount of exhaust gas carried through the heat exchanger and the bypass channel respectively, the method according to this embodiment allows to control the coolant fluid pump such that the net power gain Pnet is optimized. This allows for a more accurate control of the waste heat recovery system.
According to another embodiment of the invention, the step of determining a setpoint S2 for the mass flow lVlFcF of coolant fluid pumped through the coolant fluid pump comprises determining a power consumption Ppump of the coolant fluid pump. ln this way, also power losses occurring at the coolant fluid pump are taken into account in the optimization of the net power gain Pnet.
According to another embodiment of the invention, wherein the cooler comprises at least one radiator for cooling the coolant fluid, and a charge air cooler for cooling an air flow coming from a turbo charger and flowing through the charge air cooler toward the method further an air inlet of the combustion engine, comprises the step of: 10 15 20 25 - determining a power loss PcAc in the charge air cooler due to a temperature increase of the air flowing through the charge air cooler caused by the at least one radiator. ln this way, an even more accurate control of the heat recovery system can be achieved, since the method allows to control the waste heat recovery system such that the power losses PcAc in the charge air cooler have a minimum impact on the net power gain Pnel. The method according to this embodiment is suitable for use in a drive system in which a coolant fluid flowing through the charge air cooler is separate from the coolant fluid flowing through the at least one radiator, i.e. wherein separate closed cooling systems are used, which are arranged so that they interact with each other.
According to another embodiment of the invention, the power loss PCAC in the charge air cooler is used in the step of determining a setpoint S2 for the mass flow MFCF of coolant fluid through the coolant fluid pump. According to another embodiment of the invention, the power loss PcAc in the charge air cooler is used in the step of determining a setpoint S1 for a mass flow IVIFEG1 of exhaust gas through the first heat exchanger. Of course, it is possible to simultaneously use the power loss PcAc in the charge air cooler in the step of determining a setpoint S1 and in the step of determining a setpoint S2.
According to another embodiment of the invention, wherein the system further comprises - a second heat exchanger, 10 15 20 25 30 - a second exhaust channel connected to the first exhaust channel and configured to carry an exhaust gas originating from the combustion engine through the second heat exchanger, - a second bypass channel connected to the second exhaust channel upstream of the second heat exchanger and bypassing the second heat exchanger, - a second adjustable valve by means of which the mass flow of exhaust gas through each of the second exhaust channel and the second bypass channel can be adjusted, - a second coolant channel connected to the first coolant channel and configured to carry a coolant fluid through the second heat exchanger, the method further comprises the steps of: - determining an entrance temperature TEG2 of the exhaust gas before entry into the second heat exchanger, - controlling the second adjustable valve in response to said determined entrance temperature TEG2 of the exhaust gas before entry into the second heat exchanger. ln this embodiment, the method is used in a system comprising at least two heat exchangers, of which the first one may for example be placed in an after treatment system and the second one may for example be placed in an exhaust gas recirculation system. The method allows the exhaust gas flow through the second heat exchanger to be controlled such that damages due to high temperatures of the exhaust gases are avoided. A heat exchanger placed in the exhaust gas recirculation system may otherwise reach relatively high temperatures at which e.g. a thermoelectric generator may be damaged. 10 15 20 25 30 According to another embodiment of the invention, wherein the system further comprises a third adjustable valve connecting the first coolant channel and the second coolant channel, the method further comprises the step of: - determining a current value of the mass flow MFCF of coolant fluid pumped through the coolant fluid pump, - determining a setpoint S3 for a ratio R=MFcF1/|VlFcF2 of the mass flow MFCF1 of coolant fluid through the first heat exchanger to the mass flow MFcFz of coolant fluid through the second heat exchanger at which a net power gain Pnei of the waste heat recovery system is maximized using the determined current value of the mass flow MFCF of coolant fluid pumped through the coolant fluid pump as an input value for calculating the net power gain Pnet, - controlling the third adjustable valve so that said ratio R of the mass flows of coolant fluid is adjusted toward the determined setpoint S3. ln this embodiment, the waste heat recovery system can be controlled such that the mass flow of coolant fluid through the first and the second heat exchanger respectively is adjusted such that the net power gain Pnel is optimized. This has proved to be efficient for increasing the net power gain Pnei of the drive system, since it enables reduction of the total mass flow MFcF of coolant fluid, thereby reducing energy consumption of the coolant fluid pump.
According to another embodiment of the invention, the power loss PCAC in the charge air cooler is used in the step of determining a setpoint Se, for the ratio MFcmllvlFcrz of the mass 10 15 20 25 30 flow MFCF1 of coolant fluid through the first heat exchanger to the mass flow MFcFz of coolant fluid through the second heat This determination of the setpoint S3. exchanger. allows for increased accuracy in the According to another embodiment of the invention, the method further comprises the step of determining a torque of the combustion engine. According to another embodiment of the invention, the method further comprises the step of determining a rotational speed of the combustion engine. These embodiments enable theoretical modeling of the temperature of the exhaust gases and reduce the need for temperature sensors mounted in the waste heat recovery system, thus decreasing the complexity of the system. Preferably, both the torque and the rotational speed are determined and used for temperature modeling.
The object of the present invention is, with respect to the system, achieved by means of a waste heat recovery system for recovering waste heat from a combustion engine in a drive system according to the independent appended system claim.
Advantages and embodiments of such a system appear from the method described above and also from the following detailed desc?püon. ln other aspects, the invention also relates to a computer program having the features of claim 14, a computer program product having the features of claim 15, an electronic control unit having the features of claim 16 and a motor vehicle according to claims 17 and 18. 10 15 20 25 30 Other advantageous features as well as advantages of the present invention will appear from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS The invention will in the following be further described by means of example with reference to the appended drawings, wherein Fig. 1 shows a schematic overview of a drive system including a waste heat recovery system according to a first embodiment of the invention, Fig. 2 shows a schematic overview of a drive system including a waste heat recovery system according to a second embodiment of the invention, Fig. 3 shows a flow chart of a method according to a first embodiment of the invention, and Fig. 4 shows a schematic drawing of a control unit for implementing a method according to the invention.
DETAILED DESCRIPTION OF INVENTION EMBODIMENTS OF THE A drive system including a combustion engine 1, an after treatment system 2, and a waste heat recovery (WHR) system according to an embodiment of the invention is schematically shown in fig. 1. The WHR system includes a heat exchanger in (TEG) connection with the after treatment system 2, an exhaust channel the form of a thermoelectric generator 3 placed in 4 configured to carry an exhaust gas originating from the 10 15 20 25 30 10 combustion engine through the TEG 3, and a bypass channel 5 which is connected to the exhaust channel 4 upstream of the TEG 3 and which bypasses the TEG 3. The WHR system further includes an adjustable valve 6 by means of which the mass flow of exhaust gas through each of the exhaust channel 4 and the bypass channel 5 can be adjusted. The WHR system also comprises a coolant channel 7 connected to a cooler 8, which coolant channel 7 is configured to carry a coolant fluid through the TEG 3. A pump 9 is arranged to pump the coolant fluid through the TEG 3 and the cooler 8. ln a method for controlling the WHR system according to a first embodiment of the invention, a current value of a mass flow IVIFCF1 of coolant fluid through the TEG 3, equal to the mass flow IVIFCF of coolant fluid through the coolant fluid pump 9, is determined in a step A1, see fig. 3. This can be performed e.g. by determining the temperature increase and the pressure drop across the TEG 3 or across the pump 9, but also by sensing the mass flow MFcFi directly or by theoretical modeling. ln a step A2, an entrance temperature TEG1 of the exhaust gas before entry into the TEG 3 is determined. This can be performed either by measuring the temperature using a sensor, or by modeling using e.g. the torque and the rotational speed of the combustion engine 1 as input parameters. ln a step A3, an entrance temperature into the TEG 3 is determined. ln a step A4, a setpoint S1 for a mass flow MFaoi of Tori of the coolant fluid before entry exhaust gas through the TEG 3 is determined, at which a net power gain Pnei of the drive system is maximized. The setpoint S1 is determined using said determined entrance temperature TEo1 of the exhaust gas, said determined entrance temperature Tom of 10 15 20 25 30 11 the coolant fluid, and said determined current value of the mass flow MFCF1 of coolant fluid through the first heat exchanger as input values for calculating the net power gain Pne1. This is preferably done iteratively by first calculating the net power gain Pnet for a first test value MFEc1;m1n representing the mass flow IVIFEG1 of exhaust gas through the TEG 3, thereafter iterating for a AMFEG1, ÅMFEG1 represents a small change in mass flow MFEG1, and checking second test value MFEc-mrmn + wherein whether the net power gain Pm is larger or smaller for this second test value. As soon as a test value MFEG1;X has been found at which the net power gain Pm is at a maximum, this test value MFEcnX is output as the setpoint S1. ln a step A5, a current value of the mass flow MFEc1 of exhaust gas through the TEG 3 is determined, e.g. by a mass flow sensor (not shown) or by measuring temperature and pressure differences across the TEG 3. ln a step A6, the adjustable valve 6 is controlled so that the current value of the mass flow MFEG1 of exhaust gas through the TEG 3 is adjusted toward the determined setpoint S1 and so that the remaining exhaust gas is led through the bypass channel 5. ln this way, the WHR system can be controlled to maximize the net power gain Pne1 of the drive system. The calculation of the setpoint S1 can e.g. be carried out by a control unit (not shown) which is also used for controlling the adjustable valve 6. Before outputting the setpoint S1, it is preferably checked that the setpoint S1 represents a mass flow MFEe1 within an allowed span, so that overheating of the TEG 3 is avoided.
To further increase the net power gain Pne1 of the drive system, also a setpoint S2 for the mass flow lVlFcF of coolant fluid pumped through the coolant fluid pump 9, which here equals the mass 10 15 20 25 30 12 flow MFcFi of coolant fluid pumped through the TEG 3, can be determined. Preferably, the power consumption Ppump of the coolant fluid pump is determined for this purpose, and the setpoint S2 is calculated as the mass flow MFCF of coolant fluid pumped through the coolant fluid pump 9 that gives rise to the largest net power gain Pnei of the drive system. The coolant fluid pump 9 is controlled so that the mass flow MFCF of coolant fluid pumped through the coolant fluid pump 9 is adjusted toward the determined setpoint S2.
Another drive system including a WHR system according to the invention is shown in fig. 2. The drive system includes a combustion engine 1, an after treatment system 2 and further an exhaust recirculation system 10. The WHR system includes a first heat exchanger in the form of a first TEG 3 placed in connection with the after treatment system 2, a first exhaust channel 4 configured to carry an exhaust gas originating from the combustion engine 1 through the first TEG 3, and a first bypass channel 5 which is connected to the first exhaust channel 4 upstream of the first TEG 3 and which bypasses the TEG 3. The WHR system further includes a first adjustable valve 6 by means of which the mass flow of exhaust gas through each of the first exhaust channel 4 and the first bypass channel 5 can be adjusted. The WHR system also comprises a first coolant channel 7 configured to carry a coolant fluid through the TEG 3.
A coolant fluid pump 9 is arranged to pump the coolant fluid through the TEG 3 and a cooler including a first radiator 11 and a second radiator 12. The cooler further includes a charge air 13. The WHR system also exchanger in the form of a second TEG 14 placed in connection cooler includes a second heat 10 15 20 25 30 13 with the exhaust recirculation system 10, a second exhaust 4 and gas originating from the channel 15 connected to the first exhaust channel configured to carry an exhaust combustion engine 1 through the second TEG 14, and a second bypass channel 16 which is connected to the second exhaust channel 15 upstream of the second TEG 14 and which bypasses the second TEG 14. The WHR system further includes a second adjustable valve 17 by means of which the mass flow of exhaust gas through each of the second exhaust channel 15 and the second bypass channel 16 can be adjusted. The WHR system also includes a second coolant channel 18 for carrying coolant fluid through the second TEG 14, and a three-way adjustable valve 19 placed between the first coolant channel 7 and the second coolant channel 18, by means of which the ratio R=MFci=1IMFCF2 of mass flow of coolant fluid through the first TEG 3 and the second TEG 14 respectively can be varied. ln a method according to an embodiment of the invention, the method is implemented for the drive system shown in fig. 2. ln this embodiment, a setpoint S1 for the mass flow MFEc1 of exhaust gas through the TEG 3, a setpoint S2 for the mass flow IVIFCF of coolant fluid pumped through the coolant fluid pump 9 and a setpoint S3 for the ratio R=MFcF1/l\/lFcF2 of mass flow of coolant fluid through the first TEG 3 and the second TEG 14 respectively are set. As described above, a current value of a mass flow MFCF of coolant fluid through the coolant fluid pump 9 is determined, as well as an entrance temperature TEc1 of the exhaust gas before entry into the first TEG 3, and an entrance temperature Tcpi of the coolant fluid before entry into the first TEG 3. The power consumption Ppump of the coolant fluid pump is 10 15 20 25 30 14 also determined and used in the step of determining the setpoint S2.
Also, a power loss PcAc in the charge air cooler is determined.
This power loss PcAc is mainly due to a temperature increase of the air flowing through the charge air cooler 13 caused by the radiators 11, 12. With the air flow shown in fig. 2, the second radiator 12, placed before the charge air cooler 13, is the main source for the temperature increase in the charge air cooler 13.
The power loss PcAc is used both in the step of determining the setpoint S1 and in the step of determining the setpoint S2.
The setpoint S3 for a ratio R=MFcF1IIVIFCF2 of the mass flow MFcF1 of coolant fluid through the first TEG 3 to the mass flow lVlFcF2 of coolant fluid through the second TEG 14 is determined as the ratio R at which the net power gain Pnet of the waste heat recovery system is maximized. The setpoint S3 is determined using the determined current value of the mass flow MFcF of coolant fluid through the coolant fluid pump 9 and the power loss PcAc in the charge air cooler 13 as input values for calculating the net power gain Pnei. The three-way adjustable valve 19 is controlled so that said ratio R=MFCF1IMFCF2 of the mass flows of coolant fluid is adjusted toward the determined setpoint S3. ln this embodiment, it is also possible to determine an entrance temperature TEG2 of the exhaust gas before entry into the second TEG 14, either by means of sensing or by modeling. The second adjustable valve 17 can then be controlled in response to the determined entrance temperature TEG2. lf the temperature Tecz is too high, the second adjustable valve 17 is controlled so that all 10 15 20 25 30 15 or part of the exhaust gases are led through the second bypass channel 16. lf the temperature TEG2 is within a predetermined acceptable span, all or part of the exhaust gases are led through the second TEG 14. ln a preferred embodiment of the inventive method, it is checked S3 that the setpoint S1 represents a mass flow MFEc1 within an allowed before outputting each of the setpoints S1, S2, span, that the setpoint S2 represents a mass flow MFcF within an allowed span and that the setpoint S3 represents a mass flow ratio within an allowed span, so that overheating of each of the TEGs 3, 14 is avoided. ln a preferred embodiment of the inventive method, the setpoints S1, S2, Se, are calculated using the algorithm Alg1 presented at the end of the detailed description. ln this algorithm, the net power gain PNET is calculated for a system such as the one shown in fig. 2. ln the first for loop, a value of the mass flow IVIFCF of coolant fluid pumped through the pump 9 is set, and the power loss PcAc occurring at the charge air cooler 13 due to a temperature increase herein is determined. This loop also calculates the power loss Ppump at the pump 9, which is related to the total mass flow IVIFCF of coolant fluid pumped through the pump 9.
Inside the first for loop, the second for loop has the purpose of determining how to divide the mass flow IVIFCF of coolant fluid through the pump 9 between the first TEG 3 and the second TEG 14. The loop sets a value of the ratio R=l\/lFcF1/MFcF2 and 10 15 20 25 30 16 calculates the power gain P2 obtainable at the second TEG 14 for said ratio R.
Inside the second for loop, the third for loop steps through different mass flows MFEG1 of exhaust gas through the first TEG 3 placed in the after treatment system 2. lt calculates the power gain P1 and the power loss Pnoss in the first TEG 3, occurring due to back pressure in the after treatment system 2, and it also calculates the total net power gain Pnet by summing up all power gains and power losses.
When the third for loop is finished, a new value representing the mass flow lVlFcF of coolant fluid through the pump 9 is set and the calculations are repeated. ln this way, the net power gain Pnet will start out as a small value and will successively increase. When the net power gain Pnet starts to decrease, the iteration is aborted. The setpoints S1, S2, S3 that are output by the algorithm are the values set by the previous iteration for the mass flow IVIFEG1 of exhaust gas through the first TEG 3, for the mass flow lVlFcF of coolant fluid through the pump 9, and for the ratio R=MFcF1/MFcF2, respectively. Before sending the setpoints S1, S2, S3 to a respective control unit, it is checked that the setpoints S1, S2, S3 are within an allowed span. lf not, the setpoints are set to predefined values so that overheating of any of the TEGs 3, 14 is prevented.
The intervals of the for loops are thereafter modified by the ranges rEc1, rcF and row respectively, and moved in the direction of where the optimum is most likely to be found the next time the algorithm is run. run with a The algorithm is preferably 10 15 20 25 17 predetermined frequency, for example such that the setpoints S1, S2, Se, are updated at a frequency of 1 Hz. ln other embodiments, the method may be implemented in a WHR system in which it is only necessary to determine a setpoint S1 for the mass flow MFEG1 of exhaust gas through a first or a ln this case, single heat exchanger. the algorithm may be simplified by reducing the amount of for loops. ln a simple WHR system used in a method according to the invention, the coolant fluid may also be carried through the first and the second heat exchanger through one single coolant channel, without a three-way valve for dividing the mass flow lVlFcF of coolant fluid between the first and the second heat exchanger. ln this case, the mass flow MFCH through the first heat exchanger equals the mass flow lVlFcF through the pump located in the coolant channel.
Computer program code for implementing a method according to the invention is suitably included in a computer program which is readable into an internal memory of a computer, such as the in- ternal memory of an electronic control unit of a motor vehicle.
Such a computer program is suitably provided through a com- puter program product comprising a data storing medium read- able by an electronic control unit, which data storing medium has the computer program stored thereon. Said data storing medium is for example an optical data storing medium in the form of a CD-ROl\/I-disc, a DVD-disc, etc., a magnetic data storing medium in the form of a hard disc, a diskette, a tape etc., or a Flash 10 15 20 25 18 memory or a memory of the type ROM, PROM, EPROM or EEPROM.
Fig. 4 illustrates very schematically an electronic control unit 40 comprising an execution means 41, such as a central processor unit (CPU), for executing a computer program. The execution means 41 communicates with a memory 42, for example of the type RAM, through a data bus 43. The control unit 40 comprises also a non-transitory data storing medium 44, for example in the form of a Flash memory or a memory of the type ROM, PROM, EPROM or EEPROM. The execution means 41 communicates with the data storing medium 44 through the data bus 43. A computer program comprising computer program code for implementing a method according to the invention is stored on the data storing medium 44.
The invention is of course not in any way restricted to the em- bodiments described above, but many possibilities to modifica- tions thereof would be apparent to a person with skill in the art without departing from the scope of the invention as defined in the appended claims. 10 15 20 25 30 35 19 Algorithm A|g1: Optimization pseudo code Data: Input values from sensor signals or modeled input values Result: Outputs setpoints S1, S2, Ss for end else end MFCF = MFCRminI MFCEmax dO Remember_l\/lFcF PcAc = f Ppump = f fOr R = DiVmin: DiVmaX dO Remember_R P2 = f (...) for IVIFEG1= IVIFEGuminI IVIFEGumaX do Remember_MFEG1;m1n P1 = f (...) P1|oss= f (...) Pnet = P2 + P1' PCAC _ Plloss ' Ppump end end if Pnet < Pnet;old then Break end Remember_/MFcF/R/l\/lFEe1 in allowed span then S1 = Remember_MFEo1 é previous S2 = Remember_MFcF é previous Sa = Remember_R é previous S1 = PreDefined S2 = PreDefined Sa = PreDefined MFEGumin = S1 - FEG1 MFEGnmax = S1 + FEG1 |V|FcF;min = S2 - FcF MFCEmax = S2 + rCF ÜiVmin = S3 - foiv DiVmax = S3 + rDiv
Claims (18)
1. A method for controlling a waste heat recovery system for recovering waste heat from a combustion engine (1) in a drive system, the waste heat recovery system including: - a first heat exchanger (3), - a first exhaust channel (4) configured to carry an exhaust gas originating from the combustion engine (1) through the first heat exchanger (3), - a first bypass channel (5) connected to the first exhaust channel (4) upstream of the first heat exchanger (3) and bypassing the first heat exchanger (3), - a first adjustable valve (6) by means of which the mass flow of exhaust gas through each of the first exhaust channel (4) and the first bypass channel (5) can be adjusted, - a first coolant channel (7) configured to carry a coolant fluid through the first heat exchanger (3), characterized in that the method comprises the steps of: - determining a current value of a mass flow MFcF1 of coolant fluid through the first heat exchanger (3), - determining an entrance temperature TEG1 of the exhaust gas before entry into the first heat exchanger (3), - determining an entrance temperature TcF1 of the coolant fluid before entry into the first heat exchanger (3), - determining a setpoint S1 for a mass flow IVIFEG1 of exhaust gas through the first heat exchanger (3) at which a net power gain Pnel of the drive system is maximized using said determined entrance temperature TEG1 of the exhaust gas, said determined of the coolant fluid, and said entrance temperature TcF1 10 15 20 25 30 21 determined current value of the mass flow IVIFCH of coolant fluid through the first heat exchanger (3) as input values for calculating the net power gain Pnet, - determining a current value of the mass flow MFEc1 of exhaust gas through the first heat exchanger (3), - controlling the first adjustable valve (6) so that the mass flow IVIFEG1 of exhaust gas through the first heat exchanger (3) is adjusted toward the determined setpoint S1.
2. The method according to claim 1, wherein the step of determining the setpoint S1 for the mass flow IVIFEG1 of exhaust gas through the first heat exchanger (3) comprises the steps of: - choosing a set of test values representing the mass flow IVIFEG1 of exhaust gas through the first heat exchanger (3), - iteratively calculating the net power gain Pnei using said test values until said net power gain Pnet is at a maximum, - outputting the test value at which the net power gain Pnet is at a maximum as said setpoint S1.
3. The method according to claim 1 or 2, wherein the system further comprises a cooler (8) connected to the first coolant channel (7) and a coolant fluid pump (9), the method further comprising the steps of: - determining a setpoint S2 for the mass flow MFcF of coolant fluid pumped through the coolant fluid pump (9) at which the net power gain Pnei of the drive system is at a maximum, - controlling the coolant fluid pump (9) so that the mass flow IVIFCF of coolant fluid pumped through the coolant fluid pump (9) is adjusted toward the determined setpoint S2. 10 15 20 25 22
4. The method according to claim 3, wherein the step of determining a setpoint S2 for the mass flow IVIFCF of coolant fluid through the determining a power consumption Ppump of the coolant fluid pump (9). pumped coolant fluid pump (9) comprises
5. The method according to claim 3 or 4, wherein the cooler comprises at least one radiator (11, 12) for cooling the coolant fluid, and a charge air cooler (13) for cooling an air flow coming from a turbo charger and flowing through the charge air cooler (13) toward an air inlet of the combustion engine (1), wherein the method further comprises the step of: - determining a power loss PcAc in the charge air cooler (13) due to a temperature increase of the air flowing through the charge air cooler caused by the at least one radiator (11, 12).
6. The method according to claim 5, wherein the power loss PcAc in the charge air cooler (13) is used in the step of determining a setpoint S2 for the mass flow MFcF of coolant fluid through the coolant fluid pump (9).
7. The method according to claim 5 or 6, wherein the power loss PCAC in the charge air cooler (13) is used in the step of determining a setpoint S1 for a mass flow IVIFEG1 of exhaust gas through the first heat exchanger (3).
8. The method according to any one of the preceding claims, wherein the system further comprises: - a second heat exchanger (14), 10 15 20 25 30 23 - a second exhaust channel (15) connected to the first exhaust channel (4) and configured to carry an exhaust gas originating from the combustion engine (1) through the second heat exchanger (14), - a second bypass channel (16) connected to the second exhaust channel (15) upstream of the second heat exchanger (14) and bypassing the second heat exchanger (14), - a second adjustable valve (17) by means of which the mass flow of exhaust gas through each of the second exhaust channel (15) and the second bypass channel (16) can be adjusted, - a second coolant channel (18) connected to the first coolant channel (7) and configured to carry a coolant fluid through the second heat exchanger (14), the method further comprising the steps of: - determining an entrance temperature Tizcz of the exhaust gas before entry into the second heat exchanger (14), - controlling the second adjustable valve (17) in response to said determined entrance temperature TEG2 of the exhaust gas before entry into the second heat exchanger (14).
9. The method according to claim 8 in combination with any of claims 3-7, wherein the system further comprises a third adjustable valve (19) connecting the first coolant channel (7) and the second coolant channel (18), the method further comprising the step of: - determining a current value of the mass flow MFCF of coolant fluid pumped through the coolant fluid pump (9), - determining a setpoint Se, for a ratio R=MFCF1IIVIFCF2 of the mass flow IVIFCF1 of coolant fluid pumped through the first heat exchanger (3) to the mass flow lVlFcm of coolant fluid through the 10 15 20 25 24 second heat exchanger (14) at which a net power gain Pnet of the waste heat recovery system is maximized using the determined current value of the mass flow MFCF of coolant fluid pumped through the coolant fluid pump (9) as an input value for calculating the net power gain Pnet, - controlling the third adjustable valve (19) so that said ratio R of the mass flows of coolant fluid is adjusted toward the determined setpoint S3.
10. The method according to claim 9, wherein the power loss PcAc in the charge air cooler (13) is used in the step of determining a setpoint Se, for the ratio R=lVlFcF1/l\/lFcF2 of the mass flow MFcri of coolant fluid through the first heat exchanger (3) to the mass flow MFcm of coolant fluid through the second heat exchanger (14).
11. The method according to any one of the preceding claims, further comprising the step of determining a torque of the combustion engine (1 ).
12. The method according to any one of the preceding claims, further comprising the step of determining a rotational speed of the combustion engine (1).
13. A waste heat recovery system for recovering waste heat from a combustion engine (1) in a drive system, the waste heat recovery system including: - a first heat exchanger (3), 10 15 20 25 25 - a first exhaust channel (4) configured to carry an exhaust gas originating from the combustion engine (1) through the first heat exchanger (3), - a first bypass channel (5) connected to the first exhaust channel (4) upstream of the first heat exchanger (3) and bypassing the first heat exchanger (3), - a first adjustable valve (6) by means of which the mass flow of exhaust gas through each of the first exhaust channel (4) and the first bypass channel (5) can be adjusted, - a first coolant channel (7) configured to carry a coolant fluid through the first heat exchanger (3), characterized in that the system further comprises: - means for determining a current value of a mass flow MFcF1 of coolant fluid through the first heat exchanger (3), - means for determining an entrance temperature Tesi of the exhaust gas before entry into the first heat exchanger (3), - means for determining an entrance temperature TcF1 of the coolant fluid before entry into the first heat exchanger (3), - means for determining a setpoint S1 for a mass flow MFEc1 of exhaust gas through the first heat exchanger (3) at which a net power gain Pnei of the drive system is maximized using said determined entrance temperature Tesi of the exhaust gas, said determined entrance temperature Tom of the coolant fluid, and said determined current value of the mass flow MFcFi of coolant fluid through the first heat exchanger (3) as input values for calculating the net power gain Pnet, - means for determining a current value of the mass flow IVIFEG1 of exhaust gas through the first heat exchanger (3), 10 15 20 25 26 - means for controlling the first adjustable valve (6) so that the mass flow MFEG1 of exhaust gas through the first heat exchanger (3) is adjusted toward the determined setpoint S1.
14. A computer program comprising computer program code for causing a computer to implement a method according to any one of the claims 1-12 when the computer program is executed in the computer.
15. A computer program product comprising a data storage medium (44) which can be read by a computer and on which the program code of a computer program according to claim 14 is stored.
16. An electronic control unit (40) of a motor vehicle comprising an execution means (41), a memory (42) connected to the execution means (41) and a data storage medium (44) which is connected to the execution means (41) and on which the computer program code of a computer program according to claim 14 is stored.
17. A motor vehicle comprising an electronic control unit (40) according to claim 16.
18. A motor vehicle according to claim 17, wherein the motor vehicle is a truck or a bus.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE1451471A SE538742C2 (sv) | 2014-12-03 | 2014-12-03 | A method for controlling a waste heat recovery system and a waste heat recovery system |
| DE112015004901.0T DE112015004901T5 (de) | 2014-12-03 | 2015-11-25 | Verfahren zum Steuern eines Abwärmerückgewinnungssystems und Abwärmerückgewinnungssystem |
| PCT/SE2015/051263 WO2016089285A1 (en) | 2014-12-03 | 2015-11-25 | A method for controlling a waste heat recovery system and a waste heat recovery system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE1451471A SE538742C2 (sv) | 2014-12-03 | 2014-12-03 | A method for controlling a waste heat recovery system and a waste heat recovery system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| SE1451471A1 true SE1451471A1 (sv) | 2016-06-04 |
| SE538742C2 SE538742C2 (sv) | 2016-11-08 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| SE1451471A SE538742C2 (sv) | 2014-12-03 | 2014-12-03 | A method for controlling a waste heat recovery system and a waste heat recovery system |
Country Status (3)
| Country | Link |
|---|---|
| DE (1) | DE112015004901T5 (sv) |
| SE (1) | SE538742C2 (sv) |
| WO (1) | WO2016089285A1 (sv) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106337715B (zh) * | 2016-11-08 | 2019-04-16 | 温后东 | 一种内燃机热能回收发电装置 |
| DE102017211450A1 (de) | 2017-07-05 | 2019-01-10 | Robert Bosch Gmbh | Leistungsoptimierer für Abwärmerückgewinnungssystem |
| DE102018202919A1 (de) | 2018-02-27 | 2019-11-14 | Robert Bosch Gmbh | Regelkreis für Abwärmerückgewinnungssysteme |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8554407B2 (en) * | 2011-09-28 | 2013-10-08 | GM Global Technology Operations LLC | Bypass valve and coolant flow controls for optimum temperatures in waste heat recovery systems |
| DE102012204262A1 (de) * | 2012-03-19 | 2013-09-19 | Bayerische Motoren Werke Aktiengesellschaft | Wärmekraftmaschine in einem Kraftfahrzeug |
| FR2997446B1 (fr) * | 2012-10-30 | 2014-12-12 | Renault Sas | Procede de pilotage d'un systeme de recuperation d'energie d'une ligne d'echappement d'un moteur de vehicule automobile |
-
2014
- 2014-12-03 SE SE1451471A patent/SE538742C2/sv not_active IP Right Cessation
-
2015
- 2015-11-25 WO PCT/SE2015/051263 patent/WO2016089285A1/en active Application Filing
- 2015-11-25 DE DE112015004901.0T patent/DE112015004901T5/de not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| SE538742C2 (sv) | 2016-11-08 |
| WO2016089285A1 (en) | 2016-06-09 |
| DE112015004901T5 (de) | 2017-08-10 |
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